Egg poachers which are used on conventional top surface heaters typically consist of a metal pan, a metal tray having depressions therein, and a metal lid. Water is placed in the pan and then the tray is inserted thereover. Eggs are cracked and the contents are emptied into respective depressions. After the lid is positioned over the tray, the poacher is placed on a conventional gas surface burner or electric surface coil where the water is brought to boiling so as to heat the egg through the tray by conduction. Some heating may also result from the presence of steam at the top surface of the eggs.
The above described poacher can not be used to cook eggs in a microwave oven because the metal parts reflect microwave energy and the water would not heat to boiling. Further, if all the parts were made of a microwave transparent material, the direct exposure of the eggs to microwave energy would result in egg yolks exploding: a yolk, just like the egg shell itself, is an enclosed membrane and will explode if heated without limit. Also, if the eggs are to be shielded from microwave energy while the water is to be exposed, there is a problem preventing microwave arcing between contacting or joined metal parts that shield the eggs.